Diesel locomotives of the type having electrically-driven traction motors require wire of a size capable of carrying a current of around 1100 amps. The size of aluminum multi-strand wire having this capability is on the order of one million circular mils in cross-sectional area. The current carrying requirements and physical wire size have provided workers in the field with a problem in terminating so as to prevent terminal overheating and failure. One solution to this problem was to use heavy-walled copper terminals. However, heretofore, means of manageable size adequate to crimp a heavy-walled copper terminal around a million circular mil wire were not available, particularly when copper wire was used. In conjunction with this, aluminum wire can be used as a replacement for the copper wire offering numerous advantages, such as weight and cost savings, and reduced resistance to crimping when high pressures may be required.
As is well known, the undesirable properties of creep, cold flow, oxidation, thermal expansion and corrosion which are inherent in aluminum have to be overcome in providing a reliable and stable termination. Prior to recent developments in the field of crimp terminations for aluminum wire, welding was the only method for avoiding the aforementioned undesirable properties. This method, however, was both costly and time consuming and provided only marginal results in many instances. Now however, the development of the aluminum crimp techniques as disclosed in U.S. Pat. applications, Ser. No. 346,530, filed on Mar. 29, 1973 and Ser. No. 481,590, filed on June 21, 1974, the disclosures of both being incorporated herein by reference, teaches methods which overcome the aforementioned properties in an inexpensive manner and with excellent results. Generally and briefly, these methods provide a perforated liner between the wire and wire barrel and further use crimping forces sufficiently high to deform the terminal and wire by a factor of 65 percent. Utilizing these methods however with heavy-walled copper terminals and wire of one million circular mils in cross-sectional area presented problems, the solution to which were not obvious.
Manually operated tools capable of crimping large size terminals are heavy, bulky and generally do not provide the pressures required. Tools operated by electricity or compressed air are bulky and expensive. Further, power or compressed air is not always available at the sites where the termination is to be made.
With these limitations in mind, Applicant considered propellant-driven devices with which Applicant's assignee has some experience; e.g., U.S. Pat. Nos. 3,163,200 and 3,187,500, the disclosures thereof being incorporated herein. U.S. Pat. Nos. 2,981,130, 2,995,053 and 3,251,216, assigned to Applicant's assignee also, are additional state of the art disclosures.
It was discovered however that the tools disclosed in the aforementioned patents lacked the capabilities required. One problem was in the propellant-carrying element and means for exhausting the gases. Another problem was that of providing a method for driving the moving die out of engagement with the terminal after crimping it around the wire. The solution to these and other problems resulted in the instant invention which provides a propellant-driven device having a elongated housing whose walls define an interior chamber. One die is fixed at one end of the chamber and a second, movable die is slidingly positioned therein so that it can be driven against a terminal placed on the first die. The other end of the chamber contains a recess for receiving the rim of a cartridge containing the propellant. The cartridge is made of a plastic which, upon detonation of the propellant, separates and becomes gas-tight seals. The cap or closure means contain the firing mechanism and also a combination safety to prevent unintentional detonation and a means to seal off a gas release passageway which connects the chamber to outside the housing.